MIcrowave Landing System flight trials (and some other CAAFU photos)

The MLS was the proposed land based update for ILS. MLS allowed for variable glideslopes and curved approaches and was much less critical of siting criteria. Improvements in approach aids based on GPS have limited the adoption of MLS.

Wikipedia on MLS

more info on MLS

ILS and MLS info

The archive contains a lot of photographs on MLS and its flight, ground testing and calibration programme.

First MLS (6)MLS1

First MLS (5)MLS2

First MLS (4)MLS3

Scan_20150817 (11)MLS4

First MLS (2)MLS5

First MLS (1)MLS6

First MLS (10)MLS7

First MLS (8)MLS8

First MLS (3)MLS9

First MLS (9)MLS10

First MLS (7)MLS11

Doppler MLS landing trials at KJEVIK airport, Kristiansand, Norway


MLS (6)MLS12

Doppler MLS azimuth aerial EGKK (1)MLS13


The Doppler MLS elevation array and transmitter, developed and manufactured by Plessey, installed for trials at Gatwick. In the background, he HS748 belongs to the Royal Aircraft Establishment used during trials is seen on final approach for an automatic landing. The tented enclosure provided temporary housing for the test equipment.

 MLS (13)MLS14

MLS (8)MLS15

DMLS trials Manchester Airport

The Doppler MLS azimuth array and transmitter, developed and manufactured by Plessey, installed for flight trials at Manchester Ringway Airport. The picture shows a Royal Aircraft Establishment Andover on completion of an azimuth test flight using Doppler MLS.

 MLS BedfordMLS16

The prototype MLS evaluation system manufactured by Plessey, installed at the Royal Aircraft Establishment Bedford where it successfully underwent flight trials. The photograph shows the antennae redome removed to show the form of the radiating aperture. The height of the production antennae will be approximately 12 feet as compared to the 24 feet of the prototype.

 MLS (12)MLS17

Doppler MLS trials at Bern (Belp) Airport.

A Royal Aircraft Establishment Andover is pictured making an automatic landing on the narrow 30 metre runway at Bern (Belp) Airport in overcast conditions under landing guidance from the Plessey Doppler MLS installed. In the foreground is the DLMS elevation aerial and in the distance is a steep hill rising sharply to 1100 feet which would normally pre-empt safe landing guidance from conventional navigational aids.

 MLS (1)MLS18

The mountainous terrain on approach to Belp Airport and the close proximity to the airport of buildings, trees and pylons are clearly shown in the photos. Despite these forbidding surroundings over 50 fully automatic landings were made using DMLS. The black column in the foreground is rhe elevation array of the DMLS.

MLS (10) MLS19

MLS (4)MLS20

   The operator is using a Telecroscope which measures the actual flight path of the aircraft for comparison with the Doppler data as recorded in the aircraft’s trials equipment.

 MLS (9)MLS21

MLS (7)MLS22

Doppler MLS at Teheran (Mehrabad) Airport.

Over 70 approaches including autolands and segmented approaches were carried out recently by a Royal Aircraft Establishment HS748 during recent performance trials. The DMLS azimuth antennaes were installed and in operation within the usual 48 hours on the site which as shown in the photo had undergone only mimimum preparation.

 MLS (5)MLS23

DMLS Elevation transmitter

MLS (11)MLS24

MLS performance monitor on right

 I’ve added some additional photos of CAFU aircraft from Barry Davidson.





CAAFUprince at LAP





I can’t remember whether MJ was on a seasonal lease to Danair or this is the aircraft after CAFU disposed of it? It was I seem to remember it was unusual in that MJ was fully fitted out in airline configuration inside unlike the other 748s. Looking on line……..

“HS748 G-ATMJ CAA Dec-72 Jul-78” and “This 748, G-ATMJ was a 44 seat aircraft which gave CAA crews a more up-to -date environment in which to fly (than the DH Dove -ed).  It was also used for educational flights by Essex Schools, carried Members of the European Parliament to Luxembourg and Strasbourg as well as being leased to Dan Air at weekends. Airway reported that it had carried 42,000 passengers (4,000 of them children).”

MJ also flew with British Airways, Autair International, British Air Ferries and Emerald Airways.


Airspeed Consul G-AJXF

CAAFU1 1949 517

Avro Anson G-AHIH 1949




de Havilland Chipmunk G-ANWB









caafu g-apmo

Hunting Percival Prince G-APMO (lower shot)




Avro 748 G-AVXI

6 thoughts on “MIcrowave Landing System flight trials (and some other CAAFU photos)”

  1. A DMLS (looking very similar to that in photos MLS 7 onwards) was installed temporarily on runway 25 at Farnborough shortly after I arrived there (mid/late ’70s): I seem to recall (it was over 40 years ago) it was just left of the threshold then in use, order to help ‘disprove’ the allegation by the USA that the system could be affected by obstructions.
    We were told the building at Brussels had been planned but never constructed.
    There was another MLS temporarily installed for demonstration purposes for an airshow in the late ’90s.


  2. When I started working at RAE Farnborough in the mid-1970s, the US TRSB MLS system (that did not work at that time) had just been chosen by ICAO for deployment over the British DMLS (which worked well).
    Many of the people there had worked on DMLS & were very bitter about the ‘dirty truck’s’ employed to get that decision.
    One of these was the use of a simulation carried out by a US organisation which indicated DMLS would not work at Brussels airport due to reflection from a building in their simulation. That building never existed!


  3. Westlands bought a Hazeltine MLS for use at Yeovil and had it installed but (so I was told), management decided they couldn’t justify the cost of getting it commissioned and then flight checked every 180 days so it languished in a hangar at Yeovil; don’t know what became of it; maybe it’s still there!


  4. I still remember the 2 BA aircraft that were selected to be monitored when they made an ILS approach at Heathrow. I maybe wrong, but I think it was only applicable on 27R.

    Anyway, the 2 aircraft were G-BIKK(B757) and G-BNWB(B767).

    Whenever they made an approach on 27R we had to make them squawk 4253. They both had black and white chequered nose cones.

    It is strange the little things one remembers.

    PS Not being technically minded, I never fully understood what actually happened when they squawked that number.



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s